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Port 5687 (gog-multiplayer)

IANA assigns port 5687 to gog-multiplayer: GOG multiplayer game protocol.

Registered (user) port, 1024-49151 UDP

Port 5687 is normally used over UDP; the checker tests TCP only, so a "filtered" result does not mean the UDP service is down.

IANA assignment

Service nameProtoDescriptionAssigneeReference
gog-multiplayer UDP GOG multiplayer game protocol GOG.com -

Registry dates for this port: registered 2014-07-31, last modified 2014-10-09.

Check what is listening on port 5687

Linux: UDP 5687
sudo ss -ulnp 'sport = :5687'
Linux / macOS: which process owns the port
sudo lsof -nP -i :5687
Windows (Command Prompt)
netstat -ano | findstr :5687
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 5687

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 5687

Block port 5687 in the firewall

ufw
sudo ufw deny 5687/udp
iptables
sudo iptables -A INPUT -p udp --dport 5687 -j DROP
nftables
sudo nft add rule inet filter input udp dport 5687 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 5687' -Direction Inbound -Protocol UDP -LocalPort 5687 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.